Install openmotif in Ubuntu

I get error when install seismic unix in Ubuntu, because I dont get file Xm/Xm.h. We can solve this problem by install openmotif in Ubuntu. But, I have problem when try to get Openmotif installer in Ubuntu.
I try to use command sudo apt-cache search openmotif, but I can not get openmotif installer in Ubuntu.

After searching and try to install Openmotif in Ubuntu, I get how to solve this problem. Openmotif in Ubuntu given name by libmotif3. So, if you want to search Openmotif installer in Ubuntu, you can search by command :sudo apt-cache search libmotif

This is my output from this command :libmotif-dev – Open Motif – development fileslibmotif3 – Open Motif – shared libraries